The subject of the invention is a modular device for highly efficient and uniform blowing of gas onto the surface of the heat-treated charge, which is part of the blowing system in industrial heat treatment furnaces, in which the gas movement during convection heating and cooling is generated by mechanical means. The subject of the invention may be used in particular in the heat treatment of metal charges, e.g. in the form of sheets or foil coils made of aluminium and its alloys, steel and other metals, which are subjected to interoperational or final heat treatment processes, such as stress relief annealing and recrystallization annealing.

The heat treatment of such charges is performed using single or multichamber batch-type furnaces equipped with sets of nozzles, holes, slots, etc., symmetrically spaced on opposite sides of the process chamber and cooperating with a flow machine, e.g. a fan, creating a system blowing gas onto the charge. In order to shorten the charge annealing time, the aim is to obtain the greatest possible heat exchange in the chamber furnace. The use of blowing systems which lead to large local differences in the heat transfer is avoided as local overheating may occur which may cause, for example, discoloration of the metal strips and also have a negative effect on the metallurgical properties.

There are nozzle modules which are blowing system components, being part of the process chamber equipment in industrial furnaces or constituting separate, customized, compact devices for heat treating a narrow range of charges.

The patent No. EP1485207 describes a device for uniform blowing of gas onto a charge, in which round, evenly spaced nozzles are directed perpendicularly to the heated surface. The essential feature of said invention is a deflector inside the nozzle which swirls the outgoing gas stream.

The patent application No. EP3489602 B1 describes an invention which relates to a single-chamber, compact batch-type furnace for annealing materials and a method of heat treating these materials using this furnace. The main part of the device consists of a fan sucking air from inside the furnace, heater, and nozzles arranged concentrically around the fan. The distinguishing feature of this invention is the central opening in the plate with nozzles, constituting the inlet path of the fan. The main disadvantage of the invention is the need to precisely adjust the device for a narrow range of batches, as well as the need to use many such devices in large-scale production.

According to the German patent specification DE3503089, uniform application is achieved with the use of a rotating-symmetric device placed at the bottom of the nozzle with numerous slotted openings, the nozzle streams being inclined in the same direction in relation to the application surface. However, this requires precise centring of the charge in relation to the blowing system. The German patent specification EP0846930 describes a modular device for uniform blowing of gas onto a flat surface of a heat-treated object, consisting of a flat bottom with holes and nozzles permanently attached to this bottom, which create uniformly spaced seats on the bottom surface, each of which has the same arrangement of four nozzles placed close to each other and tilted at a proper angle. A device in the form of a channel for deflecting the nozzle streams in the range from 15 to 45 degrees is fixed at each seat nozzle opening on the device bottom. The distance between adjacent nozzle openings within the seat is smaller than the distance between each nozzle opening and the closest nozzle opening in the adjacent group. All the openings in all seats form the entirety of the nozzle openings in the bottom, and the application area of the seats in relation to the typical, total application area is small. The distance between the closest nozzle openings of adjacent seats is at least 1.5 times the smallest distance between the closest nozzle openings in the seat. The total area of the nozzle openings through which the gas is blown, when projected onto the support plate surface, is from 2% to 10% of the plate area. The appropriate configuration of the nozzle system allows for mutual interaction of gas streams flowing out of adjacent nozzles, which results in the generation of a vortex motion of the resulting gas stream and local flow turbulence. The main disadvantage of this invention is a significant decrease in the velocity of the resulting gas stream along with the increase in the distance from the nozzle outlet, which means that uniform and efficient blowing of gas onto the surface of the heat treated charge is possible only for relatively small distances between the nozzle outlet and the charge surface. Generally, known solutions are characterized by a complicated structure requiring additional devices or components operating at high temperatures, or they introduce significant flow resistance into the gas circulation system, which necessitates the use of high-power fans.

The purpose of the invention is to develop a modular device for blowing gas onto the surface of the heat-treated charge, which is part of the blowing system in heat treatment furnaces, with a structure ensuring intense, uniform and symmetrical heating and cooling of metal charges, in order to carry out the annealing process in the shortest possible time, without the risk of local overheating of individual areas of the charge, as well as with minimal energy expenditure related to the drive of the flow machine generating gas movement. The device is to ensure and optimize the heat treatment of charges, e.g. aluminium and its alloys, steel and other metals, for a wide range of charge sizes without interfering with the furnace equipment structure. In addition, the purpose of the new design of the device is to ensure relatively small changes in the dynamics and flow of the resulting gas stream, for a wide range of processed charges, especially for variable width of aluminium coils processed in the furnace chamber with constant dimensions and constant distances between nozzle units that are opposite and symmetrically located in relation to the process chamber.

A modular device for blowing gas onto the surface of the heat-treated charges, which is part of the blowing system in batch-type chamber furnaces, in which the gas movement during convection heating and cooling is generated by mechanical means and the blowing of gas onto the surface of the charge is carried out from two opposite sides of the furnace's process chamber, cooperating with a flow machine installed outside the process chamber, which sucks gas from the process chamber and then forces it through a set of channels equipped with heating elements to a modular device, in which the resulting gas stream is accelerated and properly directed to the charge surface, consisting of a rigid plate connected to the walls of the furnace's process chamber, equipped with through holes enabling gas to flow through the nozzles, and of nozzles permanently fixed on the plate surface and tilted in two directions in relation to the plate axis, characterized in that the nozzles (3) are arranged on the surface of the support plate (2) evenly with respect to the axis of symmetry (OP) of the support plate (2), forming at least two regular arrays (4), (5). The nozzles (3) are deviated circumferentially from the axis of symmetry (OP) of the support plate (2) by the angle of circumferential deviation (P) of the nozzles and centrifugally by the centrifugal angle (y). The angle of circumferential deviation (P) of the nozzles is contained between the axis of symmetry (OD) of the nozzle (3) and the straight line (ST) on the plane (P1). The straight line (ST) is tangent to the circle with the centre coinciding with the centre of symmetry (O) of the support plate (2) and with the radius defined by the point (N) of the intersection of the axis of symmetry (OD) of the nozzle (3) with the plane of the support plate (2). The centrifugal angle (y) is contained between the axis (OD) of the nozzle (3) and the straight line, located on the plane (P2), passing through the centre of symmetry (O) of the support plate (2) and the point (N) of the intersection of the axis of symmetry (OD) with the plane of the support plate (2). It is beneficial if the angle of circumferential deviation (P) of the nozzles and the centrifugal angle (y) for each nozzle (3) are the same and within the range from 45 to 89°.

It is also beneficial if the nozzles are arranged in two concentric arrays (4) and (5), with 6 to 24 nozzles in the outer array (5) and 3 to 12 nozzles in the inner array (4).

It is also beneficial if the distance between successive arrays (4) , measured along the radius of the plate, is from 1 to 6 hydraulic diameters of the nozzle (3) at the outlet.

Additionally, it is beneficial if the distance between successive arrays (4) is from 180 to 300 mm and from 18 to 32% of the plate radius length.

It is beneficial if the total area of all nozzle openings (3) in a rectangular projection onto the surface of the support plate (2) of the device is from 4 to 30% of the total area of the support plate (2) in a rectangular projection.

It is beneficial if the nozzles (3) have a circular shape in cross section.

It is also beneficial if the support plate (2) has the shape of a circle.

It is beneficial if the nozzles (3) have a rectangular shape in cross section.

It is also beneficial if the nozzles (3) are arranged on the support plate (2) in three circular arrays (4), (5), (10).

It is also beneficial if the nozzles (3) are mounted on the support plate (2) with the use of a profiled orifice acting as a confusor.

A specially designed device can cooperate in a symmetrical system with a second, equivalent device, and with an efficient fan generating gas movement in a closed system. The undoubted advantage of the invention is that it can be used in industrial conditions for high-performance and large-scale heat treatment as an optimal solution for a wide range of sheet or foil coils (with different widths, diameters of the coils, thicknesses of sheet metal, foil, etc.). The invention can be particularly useful in the heat treatment of sheets or foil coils made of aluminium and its alloys, steel and other metals carried out in single or multichamber convection furnaces.

An embodiment of the invention is shown in figures; Fig. 1 shows the furnace in cross-section with an aluminium sheet coil in the central position of the heating chamber, with a part section at the place of the fan and heating elements and one of the variants of the modules being the subject of the invention; Fig. 2 shows a view of the module from Fig. 1 with nozzle inclination angles and the plane forming the beta (P) angle; Fig. 3 shows the inclination of the nozzles with the plane forming the gamma (y) angle; Fig. 4. shows the nozzle module from Fig. 1 in a rectangular view, showing the arrangement of nozzles in arrays; Fig. 5 shows a side view of the nozzle module from Fig. 1 ; Fig. 6 shows a reference view of the nozzle of the module from Fig. 4; Figs. 6a, 6b, 6c show the nozzle projections in rectangular, top and side views, respectively; Fig. 7 shows a cross-section of a furnace with modules according to one variant, with a coil of small width; Fig. 8 and Fig. 12 show a cross-section of a furnace with modules according to selected variants, with nozzles arranged in three arrays, with different inclination angles (P); Fig. 9 and Fig. 13 show the module from Fig. 8 and Fig. 12, respectively, in a rectangular view with respect to the module arrangement in the furnace, showing the nozzle arrangement in the arrays; Fig. 10 and Fig. 14 show the nozzle module from Fig. 8 and Fig. 12, respectively, in a top view; Fig. 11 and Fig. 15 show the nozzle of the module from Fig. 8 and Fig. 12 in a reference view; Fig. 11 a, Fig. 15a, Fig. 1 1 b, Fig. 15b, Fig. 1 1 c, Fig. 15c show the nozzle projections in rectangular, top and side views, respectively; Fig. 16 shows a cross-section of a furnace with modules according to the chosen variant, with nozzles with rounded square cross-section; Fig. 17 shows the module from Fig. 6 in a rectangular view with reference to the arrangement in the furnace, showing the arrangement of the nozzles in the arrays; Fig. 18 shows the nozzle module from Fig. 16 in a top view; Fig. 19 show the nozzle of the module from Fig. 16 in a reference view; Fig. 19a, 19b, 19c show the nozzle projections in rectangular, top and side views, respectively; Fig. 20 shows the global vortex shape, the resulting gas stream, as the isosurface of the outlet velocity from the module nozzles with flow distribution on the heated coil face, in a perspective from the nozzles side; Fig. 21 shows the global vortex shape in a perspective; Fig. 22 shows schematically the flow distribution directions of individual gas streams from the module nozzles; Fig. 23 shows a heating diagram of an aluminium sheet coil treated in a furnace with modules according to the invention.

EMBODIMENTS OF THE INVENTION

Embodiment 1 : Modular device for blowing gas onto the surface of the heat- treated charge; as shown in Fig. 1 , the heat treated element is an aluminium sheet coil 9 with a width of 1600 mm located in the axis of the modules 1 , in the central part of the heating chamber 6 of the batch-type convection furnace 7, suspended on the frame by means of a steel pipe located centrally inside the coil 9. The faces 8 of the coil 9 with an outer diameter of 01850 mm and an inner diameter of 0640 mm are symmetrically spaced from the tips of the nozzles 3 by about 150 mm.

Module 1 in the form of a steel plate constituting a support plate 2 with a diameter of 1930 mm with the nozzles 3 installed on the plate surface, with an internal diameter of 120 mm and a length of 270 mm measured in the nozzle axis, arranged in two concentric circular arrays 4 and 5. The inner array 4 with a diameter of 0580 mm contains 6 nozzles 3, the outer array 5 with a diameter of 01050 mm contains 12 nozzles 3.

All axes of the nozzles 3 are inclined in the same manner, circumferentially at a P angle of 75° and centrifugally at a y angle of 88°.

Two identical modules 1 are attached symmetrically and parallel to each other on opposite sides of the heating chamber 6 of the batch-type convection furnace 7 by means of screws that form permanent and detachable connections of the modules 1 with the interior of the furnace 7 and are spaced 1900 mm apart, when measuring the distance from the tips of the nozzles 3. The support plates 2 of both modules 1 are directed parallel to the faces 8 of the sheet coil 9. The process of heating the sheet coil 9 is performed by blowing hot air from nozzles 3 onto the sheet coil faces 8. The process consists in bringing the coil 9 to the target temperature of 380°C in the shortest possible time while maintaining temperature uniformity throughout the coil volume in the range of +/- 3°C, while even local surface overheating of the coil 9 by more than 10°C is unacceptable, and then cooling the coil according to the established recipe. In order to shorten the heating time, in the first phase of the process, the heating chamber 6 is superheated in relation to the target temperature of the coil 9, and then the temperature of the heating chamber 6 is reduced to the target value of 380°C. The fan 12 sucks gas from the heating chamber 6, and then forces it through a set of channels 13 equipped with heating elements 11 to modules 1 cooperating in a pair, in which gas streams are directed and accelerated to minimum 20 m/s, as well as the global vortex (resulting gas stream) with swirling action and centrifugal action is formed, increasing the range and uniformity of the flow distribution of the resulting gas stream on the face 8 of the sheet coil 9. This process takes place continuously in a closed circuit until the set temperature of the aluminium sheet coil 9 is achieved throughout the coil volume with temperature uniformity in the range of +/- 3°C. Table 1 shows the parameters for embodiment 1 .

Table 1 . Embodiment 2: Modular device for blowing gas onto the surface of the heat- treated aluminium sheet coil 9 as in embodiment 1 , but the aluminium sheet coil 9 with a width of 1000 mm is heat treated, as in Fig. 12. Further as in embodiment 1 . The reduction of the heat transfer coefficient a [W/m ² K ^-1 ] on the face 8 of the coil 9, due to a large reduction in its width from 1600 (embodiment 1 ) to 1000 mm, does not exceed 20%, while the temperature distribution uniformity remains at a similar, very good level. Table 2 shows the parameters for embodiment 2.

Table 2. With the modular device 1 in use according to embodiments 1 and 2, it is possible to heat treat aluminium sheet coils 9 with widths preferably from 1000 to 1600 mm and with outer diameters preferably from 1600 to 1900 mm.

Embodiment 3: Modular device for blowing gas onto the surface of the heat- treated charge as in embodiment 1 , where the aluminium sheet coil 9 with a width of 2000 mm located in the axis of the modules 1 , in the central part of the heating chamber 6 of the batch-type convection furnace 7, is supported on a saddle as in Fig. 13. The faces 8 of the coil 9 with an outer diameter of 01900 mm and an inner diameter of 0700 mm are symmetrically spaced from the tips of the nozzles 3 by about 75 mm. Module 1 in the form of a steel plate constituting a support plate 2 with a diameter of 1930 mm with the nozzles 3 installed on the plate surface, with an inner diameter of 70 mm and a length of 150 mm measured in the nozzle axis, arranged in three concentric circular arrays. The inner array 4 with a diameter of 0650 mm contains 12 nozzles 3, the middle array 10 with a diameter of 01090 mm contains 24 nozzles 3, the outer array 5 with a diameter of 01530 mm contains 30 nozzles 3. All axes of the nozzles 3 are inclined in the same manner, circumferentially at a angle of 70° and centrifugally at a y angle of 70°. Further as in embodiment 1. Table 3 shows the parameters for embodiment 3.

Table 3

With the modular device 1 in use according to embodiment 3, it is possible to heat treat aluminium sheet coils 9 with widths preferably from 1600 to 2000 mm and with outer diameters preferably from 1700 to 1900 mm.

Embodiment 4: Modular device for blowing gas onto the surface of the heat- treated charge as in embodiment 3, where the faces 8 of the coil 9 with an outer diameter of 01900 mm and an inner diameter of 0700 mm are symmetrically spaced from the tips of the nozzles 3 by about 100 mm. All axes of the nozzles 3 are inclined in the same manner, circumferentially at a p angle of 45° and centrifugally at a y angle of 70°. Further as in embodiment 3. Table 4 shows the parameters for embodiment 4.

Table 4

With the modular device 1 in use according to embodiment 4, it is possible to heat treat aluminium sheet coils 9 with widths preferably from 1800 to 2030 mm and with outer diameters preferably from 1700 to 1930 mm.

Embodiment 5: Modular device for blowing gas onto the surface of the heat- treated charge as in embodiment 1 , where the aluminium sheet coil 9 with a width of 1000 mm, in the central part of the heating chamber 6 of the batch-type convection furnace 7, is supported on a saddle, the displacement of the coil axis in relation to the axis of the modules 1 is 200 mm. The faces 8 of the coil 9 with an outer diameter of 01500 mm and an inner diameter of 0700 mm are symmetrically spaced from the tips of the nozzles 3 by about 380 mm. Module 1 consists of a steel plate constituting a support plate 2 with a diameter of 1930 mm and the nozzles 3 installed on the plate surface, with rounded square crosssection with dimensions of 150 mm x150 mm x R25 and a length of 320 mm measured in the nozzle axis, arranged in two concentric circular arrays. The inner array 4 with a diameter of 0600 mm contains 5 nozzles 3, the outer array 5 with a diameter of 01120 mm contains 9 nozzles 3. All axes of the nozzles 3 are inclined in the same manner, circumferentially at a angle of 80° and centrifugally at a Y angle of 85°. Further as in embodiment 1. Table 5 shows the parameters for embodiment 5. Table 5

With the modular device 1 in use according to embodiment 5, it is possible to heat treat aluminium sheet coils 9 with widths preferably from 800 to 1200 mm and with outer diameters preferably from 1400 to 1700 mm.

If the user carries out heat treatment processes in the same furnace for a wide range of charges that differ in diameter and I or width, there is usually a noticeable difference in the efficiency of heat transfer to the charge between the cases where the charge dimensions are optimal for the heating chamber dimensions (mainly due to the fact that the coil face is close to the nozzles) and the cases where the charge dimensions are not optimal for the heating chamber dimensions, i.e. with a large distance of the coil face from the nozzles and diameters significantly different from the nozzle set diameter.

In the presented design of the nozzle set, the reduction of the heat transfer coefficient a [W/m ² K ^-1 ] on the face 8 of the sheet coil 9, due to reduction in its width from 1900 to 1000 mm, does not exceed 20%, while the temperature distribution uniformity remains at a similar, very good level despite the displacement of the axis of the coil 9 in relation to the axis of the modules 1.